Refrigeration



J. G. REID, JR

REFRIGERATION May 14, 1946.

Filed May 24 1944 ATTORNEY Patented May 14, 1946 Servel, Inc., New

Delaware 1 York, N. Y., a corporation of Application May 21, 1944, sem m. 537,057.

11 Claims.

The present invention relates to absorption refrigeration systems and more particularly to a -method of and apparatus for purging non-com.

densible gases from such systems.

While the method and apparatus of the presen invention may be used in other absorption refrigeration systems, it is particularly adapted for use in a systemof the type illustrated and described in the United States Letters Patent to Albert R. Thomas et al. No. 2,282,503, entitled Refrigeration. The absorption refrigeration system illustrated in the'Thomas et a1. patent operates in a partial vacuum and utilizes water as a refrigerant and a saline solution as 'an absorbent. In such a refrigeration system non-condensible gases may accumulate in the various elements of the system which must be purged peri odically. The exact cause of the generation of such non-condensible gases or the place where such gases are generated is not fully understood but the gases appear in all parts of the system and accumulatein'the condenser and absorber. As the condenser operates at a higher pressure. than the absorber th non condensible gases may be purged more easilyfrom the condenser than from the absorber. i

When purging such refrigeration systems it is the usual practice to connect a vacuum pump to the condenser and withdraw, the non-condensible gases therefrom. Such a purging operation requires the attention of an attendant and itis dimcult to determine when all of the non-con densible gases have been purged. To insure comaccordance with the presence or absence of noncondensible gases in the condenser to render the aspirator operative to purge non-condensible gases and inoperative to withdraw refrigerant vapor after the gases are purged.

These and other objectswill become more apparent from the following description and drawing in which like reference characters denote lik parts throughout the several views. It is to be expressly understood, however, that the drawing is for the purpose of illustration only and not a definition of the limits of the invention, reference being hacl for this purpose to the appended claims. In the drawing:

Fig. i is a diagrammatic view of'an absorption refrigeration system incorporating the novel features of 'the'present invention, and

Fig. 2 is an'enlarged diagrammatic view of the auxiliary condenser and water operated aspirator for automatically purging non-'condensible gases from the system.

in accordance with the method of the present invention a water operated aspirator is connected to a condenser in the refrigeration system for purging non-condensible gases therefrom. The condenser is arranged to receive the non-condensible gases and preferably is a separate or auxiliary unit connected to the main condenser of the system. In its broadest aspect the method plete exhaustion of all of the non-condenslble gases the operation of the vacuum pump is usually continued after the gases have been exhausted so that some of the refrigerant vapor'will be with= drawn, from the system. Such accumulative bleeding of refrigerant vapor during successive purging operations will result in'an unbalancing of the concentration of the solution in thesyst em.

One of the objects of the present invention is to provide a. method of and apparatus for automatically purging non-condensible gases from the system without withdrawing any refrigerant vapor after the gases are purged.

terflowing therethrough which, in turn, varies with the temperature of the water. As an example, let it be assumed that a pressure of 53.67 mm. Hg abs. is present in the auxiliary condenser,

' and that a resistance of 2 mm. Hg exists in the .Another object of the invention is to provide a water operated aspirator for withdrawing noncondensible gases from a. condenser connected to the refrigeration system and utilizing the-cool mg water discharged from the condenser for operating the aspirator.

Still another object of the invention is to vary automatically the temperature and vapor presconduit between the condenser and aspirator producinga critical pressure of 53.67 mm. Hg minus 2 mm, Hg or. 51.67 mm. Hg abs. at which media will flow fromthe condenser to the aspirator. If

water is supplied to the aspirator at a temperature of F. the aspirator will produce a. pressure of 49 mm. Hg abs, the vapor pressure of water at 100;FL, which is less than the-critical pras'ure of 51.5 mm. Hg sothat media will now iron the auxiliary condenser to the aspirator. .However, if-water is supplied to the aspirator at 102 F. the aspiratorwill produce a minimum pressure of only 52 mm. Hg abs., the vapor pressure of water at. 102 F.,. which is above the critical pressure of 51.5 mm. Hg so that the aspiraoff the condenser surface which they cover so that less heat will be transferred to the water. The temperature of the water supplied to the aspirator, therefore, will gradually decrease as the amount of non-condensible gases in the auxiliarycondenser increases until the comparatively low temperature of 100 F. is reached. At this low temperature the water in the aspirator will have the low vapor pressure of 49 mm. Hg abs., referred to above, so that the aspirator will be effective to produce a vacuum pressure below the critical pressure at which media will flow from the condenser to the aspirator. densible gases in the condenser then will flow to the aspirator and will be entrained in the water discharged from the aspirator.

However, when the non-condensible gases have been withdrawn from the condenser they will be displaced by condensible refrigerant-vapor. The latent heat of the refrigerant vapor will be transferred to the cooling water flowing through the condenser and the vapor will be condensed to a liquid. Due to the heat transferred from the refrigerant vapor to the cooling water the temperature and vapor pressure of the watendischarged from the condenser to the aspirator will be increased to the values of 102 F. and 52 mm. Hg abs. respectively, referred to above. When water is supplied to the aspirator at this higher vapor pressure the aspirator will not be effective to produce a vacuum pressure lower than the critical pressure at which media will'flow from the condenser. It will now be apparent that by varying the vapor pressure of the water used in the aspirator the latter will be rendered operative to purge non-condensible gases from the auxiliary condenser and rendered inoperative to withdraw refrigerant vapor after the gases have been purged. v

Referring to the drawing an apparatus for carrying out the steps of the method is shown applied to a two-pressure absorption refrigeration system similar to that illustrated and described in the Thomas et a1. patent, referred to above.

In a system of this type liquid refrigerant such as, for example, water is introduced into the upper part of an evaporator or cooling element III from a condenser II through a path of flow including a U-shaped tube 12 and flash chamber I3. The liquid refrigerant evaporates in the evap- The non-com,

ing a chamber to which steam is supplied through a conduit 25 from a. suitable source of supply. The heating of the riser tubes 23 by the steam causes refrigerant vapor to be expelled from the absorption solution and the expelled vapor is effective to raise the absorption liquid by gas or vapor-lift action.

The expelled vapor passes from the upper ends of the riser tubes 23 into a vapor separating chamber 26 having suitable bafiies 21 therein andv thence flows through a conduit 28 to the condenser II in which the vapor is liquefied. The liquid refrigerant formed in the condenser II flows by gravity 'into the U-shaped tube I2 to the upper part of the evaporator III as explained above to complete the refrigeration cycle.

The raised absorption liquid from which refrigerant vapor has been expelled is conducted from the upper part of the generator I! to the absorber I6 to absorb refrigerant vapor, this liquid being conducted to the absorber in a path of flow orator Ill with consequent absorption of heat from the ambient such as a stream of air flowing over the exterior surface of the tubes I4 and fins I5 of the evaporator. Th'e refrigerant vapor formed in'the evaporator I0 flows to an absorber Itin which the vapor is absorbed into a liquid absorbent such as, for example, a water solution of lithium chloride, lithium bromide or the like.

The absorption liquid enriched withrefrigerant is conducted from the absorber I6 to a generator I'I in path of flow including conduit I8, liquid heat exchanger I9, conduit 20, vessel 2|, and conduit 22. Within the generator H a plurality of riser tubes 23 are enclosed within ashell 24 formincluding a conduit 29, liquid heat exchanger I9, and conduit 30. The heat liberated by the absorption of refrigerant. vapor in the absorber I6 is taken up by acooling medium such as, for example, water which flows upwardly through vertically disposed banks of pipes 3| in the absorber. The cooling water is introduced into the lower end of the banks of pipes through a conduit 32 and'is discharged from the upper ends of the banks of pipes through a conduit 33. The conduit 33 is connected to the condenser II so that the cooling water also may be utilized to effect cooling of the condenser. The cooling water is discharged from the condenser I I through a conduit 33.

The system operates in a partial vacuum with generator I1 and condenser II operating at one pressure and evaporator Ill and absorber I6 operating at a lower pressure. The pressure differential between the high and low pressure sides of the system is maintained by liquid columns in the-up-leg of the U-shapedtube I2 between the condenser II and the evaporator I0 and in the conduits I8 and 30 connecting the absorber I6 and heat exchanger I9. The liquid level in the U-shaped-tube I2 is indicated by the reference character x; the liquid levels in the conduit I8 and vessel 2| connected thereto through the heat exchanger I9 are indicated by the reference characters w and 1!; and the liquid level in the conduit 29 connected to the conduit 36 through the heat exchanger I9 is indicated by the reference character 2.

During operation of" the refrigeration system non-condensible gases may accumulate in the various elements thereof. These non-condensible gases are probably formed by the chemical action of the fluids with the metallic parts of the system. Any non-condensible gases occurring in the generator H are swept into the condenser II with the refrigerant vapor flowing thereto at high velocity. The gases in the condenser II tend to accumulate adjacent its outlet end. The noncondensible gases in the evaporator ID are swept into the absorber I6 by the refrigerant as it flows 2,400,137 in Fig. l of the drawing the non-condensible gases are transferred continuously from the absorber:

i8 to the condenser II by mean of a. vessel 40 4!. A portion of the absorption liquid flowing to the upper part of the absorber; through the conduit 30 is diverted to the bottom Of the vessel 40 through a conduit 42. Preferably an apertured septum plate 43 is positioned intermediate the ends of the vessel 40 to provide'a measuring orifice for controlling the amount of absorption which draws the gases from the bottom of the I absorber into the top thereof through a conduit liquid flowing therethrough. Thus, the diverted absorption liquid is brought into intimate contact with the non-condensible gases drawn into the top of the vessel 40 throughthe conduit 4|. A vertical tube 44, which may be referred to as a fall tube pump, has a curved upper end 45 con- I nected tothe vessel 40 above the septum plate 43 with its lower end extending into a separating chamber 46. A conduit 41 is connected to the separating chamber 45 at a P t a ove the l we end of the vertical tube 44 and the opposite end of the conduit is connected to the conduit [8 leading to the heat exchanger IS. A second conduit 48 is connected to the separating chamber 45 at a point above the conduit 41 and the upper end of the second conduit is connected to the conduit 28 between the generator I1 and condenser H.

Absorption liquid flows into the bottom of the I vessel 40 and upwardly through the orifice in the septum plate 43 and into-the upper bentend 45 of the fall tube 44 until theliqu'id siphons-into the fall tube. At the end of a siphoning'operation small quantities ofnon-condens'ible gases in .the upper part of the vessel 4|! enter the upper -bent end 45 of the fall tube 44 and become trapped between successive bodies or slugs of the absorption liquid. The internal diameter of the fall tube 44 is such that gas and liquid cannot pass each other while fiowingtherethrough and the column of absorption liquid and non-condensible gases maintains the pressure differential between the high pressure and low pressure sides of the system. Thenon-condensible gases are discharged from the lower end of the fall tube 44 and bubble upwardly through the absorption liquid in the separating chamber 46 which acts to strip any refrigerant vapor therefrom and the gases escape through the conduits 48 and- 28 to the condenser II. The absorption liquid in the separating chamber 45 escapes through the conduit 41 to'the. conduit ll of the main circuit of the condensing temperature in the main condenser I I.

The auxiliary condenser 50 is connected to a' 50 and the value of the resistance must be such as to producea pressure drop between'the condenser and aspirator greater than the difference between the condenser pressure and aspirator pressure when no non-conductive gases are present. In the illustrated embodiment of the invention the check valve 5'! is shown in Fig. 2 as comprising a cylindrical vessel having a septum plate 59 of a porous ceramic material extending thereacross and provided with a, covering body of liquid 60 such as mercury on the side adjacent the aspirator 55. Such a check valve is illustrated and described in detail in the prior co- ;pending application for United States Letters Patent of Charles Alfred ,Roswell, Serial No.

- 481,729, filed April 3, 1943, entitled Valve, now Patent No. 2,363,440, issued November 21, 1944.

"The aspirator 55 has an inlet po t 6| at one end, a. restricted throat G2 intermediateits ends through which water is adapted to flow and an outlet port 53 at its opposite end towhich a discharge tube 64 is connected. The conduit 58 from the check valve .51 is connected to the aspirator '55 atthe-restricted throat 62 thereof.. v

The cooling coil 54 within the auxiliary condenser '50 has one end connectedf to an inlet conduit 66 which, in turn, isiconnected to the conduit-33" between the absorber l5 and main condenser I l for supplying cooling water thereto. A conduitfl connects the outlet from the cooling coil 54 to the inlet port 5| of the water operated aspirator 55. Preferably a. manually operable valve 88 is provided in the conduit 66 to regulate the amount of water flowing through the auxiliary condenser 50 and water operated aspirator tof compensate for variations in the temperature and pressure of the cooling water supply at different localities. One form of the invention having now been described in detail. the'mode .of operation of theapparatus is explained as follows.

During normal operation of the refrigeration the refrigeration system. Thus, the non-conden sible gases in the low pressure side of the system are transferred continuously to the condenser II where they accumulate adjacent the outlet end thereof. 4

I In accordancewith the present invention the non-condensible gases are purged from the con.-

denser I i automatically without withdrawing any refrigerant vapor after the gases are withdrawn.

Thepurging apparatusof the present invention may be used in conjunction with any suitable condenser'but preferably an auxiliary condenser 50 is provided which is connected tothe main system steam will be supplied to the generator I! through the conduit 25 which will vaporize refrigwant in the tubes '23. The vaporized refrigerant will rise through the separating chamber 26 and conduit 28 into the condenser l l where the vapor will condense to a liquid. The liquid refrigerant will fiow from the outlet of the condenser H through the U-shaped tube l2 and flash chamber B into the evaporator 10 where the liquidrefrigerant will evaporate to produce refrigeration.

Refrigerant vapor in the evaporator Ill will flow to the absorber l6 where it will be absorbed in the absorption solution therein. The dilute abcondenser ll; adjacent its outlet by means of a conduit 5|. The auxiliary condenser 50 is in' the form of a cylindrical shell forming a closed chamber and having a water cooled coil 54 therein.

,Preferably the auxiliary condenser is so constructed-and arranged as .to condense refrigerant vapor at a temperature slightly lower than sorption solutionwill flow continuously from-the absorber I5 through the conduit l8, heat exchanger l9, conduit 20, chamber 21. and conduit 22 back to thebase of the generatorll. Simultaneously theconcentrated absorption solution in the. separating chamber 26 will flow through the conduit 29 heatexchanger l9. and conduit 30,-back into the absorber l6. J

During the operation of the refrigeration syspor will gradually accumulate therein.

tem any non-condensible gases occurring in the generator l1 will be carried into the condenser H with the refrigerant vapor. Simultaneously any non-condensible gases occurring in the evaporator III wm be swept into the absorber IS with the refrigerant vapor and will. accumulate at Also during operation of the refrigeration systern part of the cooling water flowing through the conduit 33 from the absorber l6 to the condenser II will be diverted through the conduit 66 to the cooling coil 54 of the auxiliary condenser 50 and will flow from the cooling coil through the conduit 61 to the inlet port 6| of the water operated aspirator 55. The valve 68 will be initially adjusted to cause the proper amount of water tobe supplied to the auxiliary condenser 50 to give the proper temperature differential to the water entering and leaving the latter. Due to the flow of the cooling water through the aspirator 55 a partial vacuum will be created at the throat 62 of a value depending upon the vapor pressure of the water. In other words, the water in the aspirator 55 will vaporize when a predetermined low pressure is reached and the pressure at which the water vaporizes is dependent upon its temperature.

The non-condensible gases flowing into the auxiliary condenser 50 with the refrigerant va- As the gases are non-condensible little or no heat will be transferred from thegases through the cooling coil 54 to the water-flowing therethrough. As a result, the temperature of the cooling water discharged from the auxiliary condenser 50 will gradually decrease in proportion to the increasing surface area of the auxiliary condenser blanketed by the non-condensible gases. As the vapor pressure of the cooling water decreases with the temperature the pressure produced by the aspirator will be reduced gradually in accordance with the amount of non-condensible gases in the auxiliary condenser until it is lower than the pressure in the condenser less the pressure drop due to the check valve 51. When this ,low pressure in the aspirator 55 occurs the noncondensible gases in the auxiliarycondenser 50 will flow therefrom through the conduit 56, po-

rous septum plate 59 of the check valve 51 and conduit 58 into the aspirator 55 where they will be entrained in the water passing therethrough and exhausted through the discharge tube 64.

The flow of non-condensible gases-from the auxiliary condenser 50 will continue and the gases will be displaced by refrigerant vapor flowing thereto from the main condenser H. -When refrigerant vapor enters the auxiliary condenser 50 heat will flow from the high temperature va-' por to the relatively low temperature water in the cooling coil'54 causing the refrigerant vapor to.liquefy. Due to the transfer of the latent heat of vaporization of the refrigerant vapor to the cooling water in the cooling coil 55 the temperature of the cooling water will rise which, in

the aspirator 55 cannot reduce the pressure at the throat 62 to a value below thecritical pressure necessary to cause a flow from the-auxiliary condenser 50. As the pressure in the aspirator 55 is above the pressure occurring in the auxiliary condenser 55 less the resistance of the check valve 51 refrigerant vapor will not flow from the condenser to the aspirator. Water vapor from the aspirator or atniospheric air, however, is prevented by the check valve 51 from flowing to the auxiliary condenser 59.

As an example, the following operating conditlons of a particular unit are given as illustrative. Case I indicates the conditions when no non-condensible gases .are present in the auxiliary condenser and Case II indicates the conditions when the auxiliary condenser is filled to maximum capacity with non-condensible gases.

MAIN CONDENSER CONDITIONS IN BOTH CASE I AND CASE II 1. Cooling water inlet..- Q F.- 95 2. Cooling water outlet... F 103 3. Condensing temperature F.. 104 4. Condensing pressure (at 104) mm. Hg abs" 55. 32

Case I A. Auxiliary condenser:

1. Cooling water-inlet F 95 2. Cooling water outlet F 102 .3. Condensing temperature" F 103 4. Condensing pressure (at 103 1:. mm. Hg abs 53. 67 5. Resistance of check valve mm. Hg 2 6. Critical pressure (53.67 mm. Hg-2 mm. Hg)

h mm. Hg absu 51. 61 7. Difference in pressure between main and auxiliary condensers mm. Hg.. 1.65 B. Aspirator:

1. Water inlet F 102 2. Lowest possible pressure (at 102 F.) .mm. Hg abs" 52 Case II A. Auxiliary condenser:

1. Cooling water inlet F 95 2. Cooling water outlet F 95 3. Actual temperature in auxiliary condenser F 95 4. Actual pressure in auxiliary condenser (main condenser pressure) mm. Hg abs. 55. 32 5. Resistance of check valve mm. Hg 2 6. Critical pressure (55.32 mm. Hg-2 mm. Hg)

mm. Hg abs" 53. 32 B. As irator: i

1. star inlet F 95 2. Lowest possible pressure (at 95 F.)- mm. Hg abs-. 42

As the condensing pressure in the main condenser I I will be maintained substantially constant at 55.32 mm. Hg abs. the actual pressure occurring in the auxiliary condenser 50 will be substantially the same as that in the main condenser when the auxiliary condenser is filled to capacity with non-condensible gases and no condensation can occur. The check valve 51 will add approximately 2 mm. Hg resistance to the flow of gases from the auxiliary condenser 50 so that the critical pressure or, in other words, the actual pressure to be overcome by the aspirator 55 when no gases are present will be 53.67 mm. Hg abs. minus 2 mm. Hg or 51:67 mm. Hg abs. When non-condensible' gases are present in the auxiliary condenser 50 water will be supplied to the aspirator at 102 F. which will permit the aspirator 55 to produce a theoretical vacuum pressure of only -While the aspirator may not reach the vapor pressure of the water flowing therethrough, for purposes of description the vapor pressure oi 55.32 mm. Hg abs. the non-condensible gases will flow from the condenser to the. aspirator;

In actual practice the aspirator 55 will operate at temperature and vapor pressure values between those cited above in Case I and CaseII at which.

time both non-condensible gases and refrigerant vapor will be present in the auxiliary condensertiil. When the temperature of the cooling water in the aspirator 55 decreases to produce a, pres- I sure less than the critical pressure of 51.67 mm.

Hg abs, referred to in'Case 1, some non-con densible gas will be withdrawn from the auxiliary condenser 50 and the greater the decrease in the aspirator pressure the greater will be theamount of gaswhich flows to the aspirator. Thus the having a condenser and water operated aspirator connected to the condenser which comprises supplying water to the aspirator at such a temperature that its vapor pressure is above the pressure at which media will flow from the condenser to the aspirator, and decreasing the temperature and vapor pressure of the water supplied to the aspirator in response to the presence of noncondensible gases in the condenser so that the aspirator will produce a pressure below the pressure at which media in the condenser will flow .to the aspirator whereby to withdraw the noncondensible gases fromithe condenser.

A 3. The method of purging. non-condensibl e gases from an absorption refrigeration system having a condenser and a water operated aspirator connected to the condenser which comprises flowing coolingw'ater through the condenser and aspitemperature and vapor pressure of the cooling i water flowing through the aspirator 55 will gradually decrease until a condition'of equilibrium is reached at which time the non-condensible gases will be withdrawn from the auxiliary condenser 50 asrapidly as they enter the condenser.

The actual pressure produced by the aspirator 55 willbe only a few mm. Hg below the critical pressure at which the gases will start to flow to the aspirator.

'Ityvill now be tion provides a method of and apparatus for automatically purging non-condensible gases from the refrigeration system without withdrawing any refrigerant vapor after the gases have been withdrawn. It also willbe observed that the present invention utilizes the cooling water ordinarily used so that the automatic purging. mechanism of the present invention will not add to the cost of operation of the'system". It still further will be observed that the present'invem rator successively tovary the temperature of the water in the aspirator in accordance with the amount of condensation of refrigerant vapor occurring in the condenser, the vapor pressure of the water varying with said temperature to a value above -and below the pressure at which media will flow from the condenser to the aspirator whereby said aspirator is operative automatically to withdraw non-condensible gases from the condenserand is inoperative to withdraw refrigerant vapor after the gases have been withdrawn.

observed that the present invention provides for varying the vapor pressure of the water in a water operated aspirator to a value above or below the critical pressure at whichmedia will flow from the condenser in accordance with the-absence or presence of non-condensible gases therein.

While the method and a preferred form of apparatus are herein illustrated and described, it will be understood by those skilled in the art that various changes-may be made-in the steps of the method and in the construction and arrangement of the parts of the apparatus without departing from the spirit or scope of the invention as set forth with following claims.

I claim:

l. The method of purging -non-condensible gases from an absorption. refrigeration system, having a condenser and a water operated aspirator connected to the condenser which comprises flowing water through the. aspirator, and varying the temperature and vapor pressure of the water flowing through the aspirator inaccordance with the presence or absence of non-condensible gases in the condenser whereby said aspirator is operative to withdraw non-condensible gases from the condenser and inoperative to withdraw any refrigerant vapor after the gases are withdrawn.

4; The method of purging non-condensible gases from an absorption refrigeration system having a condenser and water operated aspirator connected to the condenser which comprises continuously transferring non-condensible gases. from the various parts of the system tothe condenser, flowing cooling water through the condenser and aspirator successively to vary the tem perature of the water in the aspirator in accordance with the amount of condensation of refrigerant vapor occurring in the condenser, the vapor pressure of the water varying with said temperature to a valueabove and below the pressure at which media in the condenser will flow to the aspirator whereby said aspirator is operative au-- tomatically to withdraw non-condensible gases from the condenser and is inoperative to withdraw refrigerant vapor after the gases have been withdrawn.

5. In an absorption refrigeration system in which non-condensibl'e gases occur, a generator, a condenser, an evaporator, an absorber, means interconnecting theelernents to provide a closed circuit for the circulation of -a refrigerant and absorbent,-and an auxiliary condenser connected tosaid system for receiving and segregating noncondensible gases therein, a water operated aspirator connected to said-auxiliary condenser, and

means for flowingcoolingwater through the I auxiliary condenser and aspirator successively whereby said aspirator is operative to automatically withdraw non-condensible gases from the condenser without withdrawing refrigerant vapor after the-non-condenslble gases have been withdrawn. 7

6. In an absorption refrigeration system in which non-condensible gases may occur, a gem erator, a condenser, an evaporator, an absorber, means interconnecting the elements to provide I .a closed circuit for the circulation of a refrigerant 2. The method of. purging non-condensible gases from 'an" absorption refrigeration system and absorbent, an auxiliary condenser connected to said system for receiving and segregating noncondensible gases therein, a water operated aspirator connected to said auxiliary condenser, and means for supplying water in a path of flow through the auxiliary condenser and aspirator or absence of non-condensible gases in the auxiliary condenser to produce a pressure in the aspirator below or above the pressure at which media will flow from the condenser to the aspirator whereby the aspirator is operative to withdraw non-condensible gases from the condenser without withdrawing refrigerant vapor therefrom after the gase have been withdrawn.

7. In a two pressure absorption refrigeration system of the type which operates in a partial vacuum and in which non-condensible gases may accumulate, means for transferring non-condensible gases from the low pressure side to the high pressure side of the system while maintain'ing the pressure differential, a condenser connected to the high pressure side of said system to receive and segregate the non-condensible gases, a water operated aspirator connected to said condenser, conduits providing a path of flow for water through the condenser and aspirator successively, and a check vaivein the conduit connecting the condenser and aspirator.

8. In an absorption refrigeration system having a plurality of elements interconnected to provide a closed circuit for the circulation of a refrigerant and-absorbent and in which non-condensible gases may occur, a purge device including a condenser connected to said system for receiving and segregating non-condensible gases, a water operated aspirator connected to said condenser, conduits for supplying water in a path of flow. through the condenser andaspirator suc-'- cessively, and a check valve between the condenser and aspirator for permitting the flow of gases from the condenser to the aspirator while preventing the flow of gases from the aspirator to the condenser, the temperature and vapor pressure of the water in the aspirator varying in accordance with the presence or absence of noncondensible gases in the condenser to produce a flow through the auxiliary condenser and water operated aspirator successively, the temperature and vapor pressure of the water in the aspirator varying to produce a pressure in the latter above and below the pressure at which media will flow from the auxiliary condenser to the aspirator depending upon the amount of condensation occurring in the auxiliary condenser whereby the aspirator is operative to withdraw non-condensible gases from the auxiliary condenser without withdrawing any refrigerant vapor therefrom after the gases have been withdrawn.

10. In an absorption refrigeration system comprising a generator, a condenser, an evaporator, an absorber, means interconnecting the elements to provide a closed circuit for the circulation of a refrigerant and absorbent, means for transferring non-condensible gases from the absorber to the condenser, a water Operated aspirator connected to the condenser, and means for supplying cooling water in a path of flow through the condenser and aspirator successively, the temperature and vapor pressure of the water in the after the gases have been withdrawn.

11. In an absorption refrigeration system comprising a generator, a main condenser, an evap- 40 denser, an auxiliary condenser connected to the pressure in the aspirator below or above the presrator,- an absorber, means interconnecting the elements to provide a closed circuit for the circulation of a refrigerant and absorbent, an auxiliary condenser connected to the main condenser adjacent the outlet therefrom, a wateroperated aspirator connected to the auxiliary condenser,

conduits for supplyin cooling water in a path of main condenser adjacent its outlet, a water operated aspirator connected to the auxiliary c0n-' denser, conduits for supplying cooling water in a path of now throughthe auxiliary condenser and water operated aspirator successively, the temperature and vapor pressure of the water in the aspirator varying to produce a pressure in the latter above and below the pressure at which media will flow from the auxiliary condenser to the aspirator depending upon the amount of condensation of refrigerant vapor occurring in the auxiliary condenser whereby the aspirator is operative to withdraw non-condensible gases from the auxiliary condenser without withdrawing any refrigerant vapor therefrom after the gases have been withdrawn.

' JOHN G. REID, JR. 

